Something like a foreign exchange market cannot help determine this right?
In theory, could the exchange rate for $1 be made equal to 1,200 carolus guilders? (Effectively, making the bonds worthless)
If you want to treat it like a completely separate coin, you'd have to buy historical carolus guilders in auctions. They seem to be worth about €1500 [0], although the same amount of gold can be bought for only €240.
When the Dutch florin was introduced there would have been an agreed (or imposed) exchange rate. Looks like that was 1:1.
Later when the Euro was adopted there was an exchange rate for that too.
To get to USD use the floating exchange rate of the open market.
https://en.wikipedia.org/wiki/2016_Indian_banknote_demonetis...